Creation EAN / UCC - 13 in Software NOTE

Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications.

TarCode.com/UPC - 13

Remember this mantra: An index is not a key. You can define unique indexes (see 18 for details), but making a unique index does not create a unique key. If there is a chance that you might need to use a uniquely indexed column or structure as a key, consider defining the constraint instead.

Using Barcode printer for Software Control to generate, create Code 39 Extended image in Software applications.

TarCode.com/ANSI/AIM Code 39

Using Barcode printer for Software Control to generate, create QR-Code image in Software applications.

In the current SQL argot, Firebird supports the external virtual table, or EVT. Filesystem files in ASCII text format can be read and manipulated by Firebird as if they were tables, albeit with considerable limitations arising from the fact that they are not internal database objects. Other applications can thus exchange data with a Firebird database, independent of any special transforming mechanism. External tables can be converted to internal tables. The EXTERNAL FILE clause enables a table to be defined with its row structure mapping to fixed-length fields in records (usually delimited by line feeds) that reside in an external file. Firebird can select from and insert into such a file as if it were a regular table. It cannot, however, perform update or delete operations on external tables. The text file containing the data must be created on or copied to a storage device that is physically under the control of the server as usual, no NFS devices, shares, or mapped drives. Shared access by Firebird and other applications at the file level is not possible. Firebird requires exclusive access during times when it has the file open in a transaction. At other times, the file can be modified by other applications.

Using Barcode creator for Android Control to generate, create GTIN - 13 image in Android applications.

TarCode.com/EAN13

Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.

TarCode.com/GTIN - 13

Syntax for CREATE TABLE...EXTERNAL FILE

Using Barcode creation for Font Control to generate, create QR image in Font applications.

Using Barcode maker for Reporting Service Control to generate, create UPC-A Supplement 2 image in Reporting Service applications.

TarCode.com/GTIN - 12

The CREATE TABLE statement for an external file defines both the external file specification (local location and file name) and the typed Firebird columns represented by the structure of the contained records.

filespec is the fully qualified local path and file specification for the external data file. The file need not exist at the time the table is created. However, from Firebird 1.5 onward, the CREATE statement will fail if the filespec refers to an unconfigured external file location. See the section Securing External Files later in this chapter and the configuration section in 36. columndef is an ordinary Firebird column definition. Non-character data types can be specified, provided every string extracted from the column s location in the external record is capable of being cast implicitly to that type. line_delimiter is an optional final column or pair of columns that can be defined to read the characters used by the file system to mark the end of a line of text. Although it makes reading the file easier for humans, it is not a requirement in a fixed-format record unless programs that are going to read the data require it. On Linux/UNIX, this is the single character ASCII 10, the line feed character. On Windows, it is the ordered pair ASCII 13 (carriage return) followed by ASCII 10.

Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.

Using Barcode drawer for Reporting Service Control to generate, create UCC.EAN - 128 image in Reporting Service applications.

TarCode.com/GS1 128

On Mac OS, it is ASCII 10 followed by ASCII 13. Other operating systems may use other variations or other characters.

Restrictions and Recommendations

Securing External Files

With all versions of Firebird, a list of directories can be configured to restrict the locations where Firebird will search for or create external files. See 3 for the configuration parameters ExternalFileAccess in firebird.conf (for v. 1.5 servers) or external_file_directory in ibconfig/isc_config (for v. 1.0.x). By default, Firebird 1.5 is installed with no access to external files, whereas 1.0.x gives open access to any file in the local filesystem.

NOTE

The method of configuration and the capability to protect the system from malicious attack via external file access differ between server versions.